The commercial distribution and injection of the proteolytic enzyme chymopapain for the non-surgical treatment of prolapsed intervertebral discs has recently obtained regulatory approval, and use of this method to replace traditional disc surgery is rapidly increasing. Many patients injected with chymopapain, however, have shown symptoms of anaphylactic hypersensitivity, ranging from mild urticaria to circulatory collapse and death. The injection of a high concentration of enzyme into the disc greatly accentuates the hypersensitivity reaction and can cause fatal reactions. Allergic hypersensitivity to chymopapain is now believed to be present in as much as one percent of the total population, perhaps because of frequent ingestion of chymopapain in foods such as papaya, pinapple, and particularly tropical fruit juices. Anaphylactic shock is therefor a major, serious risk associated with this new treatment.